1. Field of the Invention
This invention relates to a linkage structure for tilting the frames of a centrallyarticulated two-sectioned truck chassis.
2. Description of the Prior Art
Truck frames having tiltable beds are widely used for hauling many types of cargo, such as disabled automobiles, farm implements, tractors and the like. Certain types of these trucks, in particular, have a front, cab-supporting frame pivotally joined to a rear frame, the frames operable to simultaneously buckle upwardly about central pivot therebetween. Additionally, the rear frame has a reciprocable bed which is extended toward the ground when the truck frames are swung upwardly at the pivot. Such two-sectioned, pivotally connected truck frames are highly useful because the angle of inclination of the cargo-supporting bed is sufficiently low to provide clearance for loading the vehicles and other cargo to be hauled.
In the past, two-sectioned truck chassis have been provided with various structures for tilting the frames. The disclosure in U.S. Pat. No. 2,466,452, issued to Edward Lisota, illustrates the use of a hydraulic power assembly mounted on the front frame, the assembly having an upwardly extensible piston rod coupled to the reciprocable bed.
In a related pending U.S. application, Ser. No. 06/600,951, filed Apr. 16, 1984 and entitled "Automatic Truck for Hauling Goods", now U.S. Pat. No. 4,556,357, the cylinder and piston assembly is pivotally mounted on the rear frame and connected by a system of linkage to the front frame, the linkage and power assembly overlying the pivotal axis of the frames. The linkage system is comprised of a set of triangular links pivotally mounted on the rear frame, and a generally crescent shaped control link is pivotally connected to the triangular links and to the front frame. As the power assembly swings the triangular links upwardly, the control link simultaneously moves upwardly and forwardly, resulting in opposite tilting of the frames about their pivotal axis. After the cargo is loaded, the power assembly reversely swings the triangular links, pulling the frames downwardly until the latter return to their normal, horizontal position.